Hemodynamics
LV and PCWP
Obtaining matching pressures of the Left Ventricle and PCWP will give you greater information related to the Mitral Valve. Two conditions to be examined are Mitral Regurgitation and Mitral Stenosis.
Mitral Regurgitation
An incompetent mitral valve, in which the valve leaflets do not completely close or protrude back into the left atrium, will cause a backflow of blood from the left ventricule into the left atrium during ventricular contraction. This results as an elevated v wave on the PCWP tracing.
Mitral Stenosis
The narrowed mitral valve, caused by stenosis, restricts blood flow from the left atrium into the left ventricle. This condition causes an augmentation in the y descent of the v wave.
Mitral Valve Area
- mild mitral stenosis = 1.5 - 2.0 cm2
- moderate mitral stenosis = 1.0 - 1.5 cm2
- severe mitral stenosis = < 1.0 cm2
Calculating Mitral Valve Area: valve flow (ml/sec) / K * C * √ mean valve gradient
K is a Gorlin constant = 44.3. C is an empirical constant = 0.85 for the mitral valve
- Part 1: Calculate diastolic filling period (DFP) and convert to seconds. The DFP is the length between the initial PCWP and LV crossover in early diastole to the point of end diastole (peak of R wave). That length is then divided by paper speed.
- Part 2: Calculate the mitral valve flow (MVF). MVF = C.O.(l/min) * 1000 / DFP * HR
- Part 3: Calculate mean valvular gradient (MVG). MVG = planimetry area * scale factor / DFP. A simplified formula for MVG = mean LAP(or PCWP) - (LVEDP / 2).
- Part 4: Calculate the mitral valve area (MVA). MVA = mitral valve flow (ml/sec) / K * C * √ mean valve gradient
References
- Baim, D.S. (2005) Grossman's Cardiac Catheterization, Angiography, and Intervention. (7th ed.). Philadelphia,Pa: Lippincott, Williams & Wilkins.
- Daily, E.K. and Schroeder, J.S. (1990) Hemodynamic Waveforms - Exercises in Identification and Analysis (2nd ed.). Philadelphia, PA: Mosby.
- Kern, M. et al (2003) The Cardiac Catheterization Handbook (4th ed.). Philadelphia, Pa: Mosby.
